Paintable material

ABSTRACT

A sealant material and articles incorporating the same. The sealant material includes up to about 80% of an epoxy resin; up to about 40% of an epoxy/elastomer hybrid; up to about 40% of a rheology modifier; up to about 5% of a blowing agent; up to about 7% of a curing agent; and about 40 to about 60% of a filler.

FIELD OF THE INVENTION

[0001] The present invention relates to paintable materials, andparticularly sealant materials for covering a surface.

BACKGROUND OF THE INVENTION

[0002] Sealant materials are often applied to surfaces for sealing orfor otherwise covering the surface, including any joints associatedtherewith. There presently exist a vast number of sealant materials thatserve these purposes for different articles of manufacture. However, incertain circumstances, it may be desirable for sealant materials toserve other additional purposes depending on the components or articlesof manufacture to which the sealant materials are applied.

[0003] For example, in some industries, such as the furniture, applianceor automotive industries, joints are typically part of a show surface,and are thus visible to a user or consumer. Accordingly, one desirablecharacteristic for a sealant for covering the joint is to provide agenerally smooth or continuously or controlled patterned surface that iscosmetically pleasing. If colorant is not already included in thesealant, but a color is desirable, preferably the sealant material ispaintable.

[0004] Certain assembly operations in the aforenoted industries andothers, require that a sealant be heated along with the article to whichit is applied. For instance, some priming or painting operations areconducted at elevated temperatures. Thus, another desirable trait forcertain sealants is that they exhibit attractive temperature responsecharacteristics for a desired application. For example, a metal shelvingunit having a sealant applied to a joint thereon, upon heat exposure,advantageously will not experience random oozing, bubbling, rippling, orthe like, which would require post treatment clean-up processes.

[0005] Further, in certain applications it may also be desirable for thesealant material to self level or otherwise flow in a predeterminedmanner during or after application of the material such that the sealantcan properly function.

SUMMARY OF THE INVENTION

[0006] The present invention meets the above needs by providing animproved paintable sealant material, and articles incorporating thesame, including:

[0007] (a) an epoxy resin material;

[0008] (b) an epoxy/elastomer mixture;

[0009] (c) a rheology modifier

[0010] (d) a blowing agent;

[0011] (e) a curing agent; and

[0012] (f) a filler.

[0013] The sealant material and methods of using it disclosed herein areparticularly adapted for enabling the material to be painted usingconventional or art-disclosed coating techniques.

[0014] The sealant material may be applied to a surface, or to jointswithin or between one or more surfaces. In some applications, thesealant material can be used for bonding a first surface to a secondsurface. The sealant material is extrudable, moldable, or processableusing other art-disclosed techniques. In one particularly advantageousaspect, the sealant material is used for sealing or otherwise coveringvisible joints or hems on articles of manufacture such as, refrigeratordoors, range tops, dishwashers, freezers, microwave ovens, desk tops,desk drawers, chair bumpers, filing cabinets, shelving, or the like.

[0015] The sealant material alternatively is applied to a variety ofcomponents of an automotive vehicle such as hem flanges, fuel fillerdoors, fuel filler assemblies, license plates, doors, door frames,ditches, vehicle grille assemblies, bumper guards, consoles, nameplates, badges or the like. Moreover, in certain embodiments, thesealant material is attached to a substrate of a component as a separatepre-formed seal, e.g., molded into a desired configuration.

[0016] One additional particularly attractive feature of the presentinvention is the ability, in some applications, to employ the sealantmaterial by itself and without any separately fabricated supportsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The features and inventive aspects of the present invention willbecome more apparent upon reading the following detailed description,claims, and drawings, of which the following is a brief description:

[0018]FIG. 1 illustrates a sectional view of an exemplary sealantmaterial formed in accordance with an aspect of the present invention;

[0019]FIG. 2 illustrates a sectional view of the sealant material ofFIG. 1 after a portion of the sealant material has been cured accordingto another aspect of the present invention;

[0020]FIG. 3 illustrates a sectional view of the sealant material ofFIGS. 1-2 as applied to an example of a substrate;

[0021]FIG. 4 illustrates a sectional view of the sealant material ofFIGS. 1-3 after the material has flowed onto the substrate;

[0022]FIG. 5 illustrates an example of how an extruder might be used toform and/or apply the sealant material of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] The present invention is predicated upon an improved sealantmaterial, and articles incorporating the same, including:

[0024] (a) up to about 80% of an epoxy resin;

[0025] (b) up to about 40% of an epoxy/elastomer;

[0026] (c) up to about 40% of a rheology modifier;

[0027] (d) up to about 5% of a blowing agent;

[0028] (e) up to about 7% of a curing agent; and

[0029] (f) a filler.

[0030] Percentages herein refer to weight percent, unless otherwiseindicated.

[0031] Epoxy Resin

[0032] Epoxy resin is used herein to mean any of the conventionaldimeric, oligomeric or polymeric epoxy materials containing at least oneepoxy functional group. The polymer based materials may be epoxycontaining materials having one or more oxirane rings polymerizable by aring opening reaction. In preferred embodiments, the sealant materialincludes up to about 80% of an epoxy resin. More preferably, the sealantincludes between about 10% and 50% by weight of epoxy containingmaterials.

[0033] The epoxy containing materials may be aliphatic, cycloaliphatic,aromatic or the like. The epoxy may be supplied as a solid (e.g., aspellets, chunks, pieces or the like) or a liquid (e.g., an epoxy resin).The epoxy may include an ethylene copolymer or terpolymer that maypossess an alpha-olefin. As a copolymer or terpolymer, the polymer iscomposed of two or three different monomers, i.e., small molecules withhigh chemical reactivity that are capable of linking up with similarmolecules. Preferably, an epoxy resin is added to the sealant materialto increase the flow properties of the material. One exemplary epoxyresin may be a phenolic resin, which may be a novalac type or other typeresin. Other preferred epoxy containing materials may include abisphenol-A epichlorohydrin ether polymer, or a bisphenol-A epoxy resinwhich may be modified with butadiene or another polymeric additive.

[0034] Epoxy/Elastomer

[0035] In a highly preferred embodiment, one or more of the epoxycontaining materials may be provided to the sealant material as anepoxy/elastomer hybrid, e.g., a blend or copolymer that has beenpreviously fabricated. The epoxy/elastomer hybrid may be included in anamount of up to about 40% by weight of the sealant material. Morepreferably, the epoxy/elastomer hybrid is approximately 10 to 30%, andmore preferably is about 20% by weight of the sealant material.

[0036] In turn, the hybrid itself generally includes about 1:5 to 5:1parts of epoxy to elastomer, and more preferably about 1:3 to 3:1 partsor epoxy to elastomer. In one preferred embodiment, the epoxy/elastomerhybrid preferably includes approximately 40 to 80% of an epoxy resin(such as disclosed in the above), and about 20 to 60% of an elastomercompound. The elastomer compound may be any suitable art disclosedthermoplastic elastomer, thermosetting elastomer or a mixture thereof.Exemplary elastomers include, without limitation natural rubber,styrenebutadiene rubber, polyisoprene, polyisobutylene, polybutadiene,isoprene-butadiene copolymer, neoprene, nitrile rubber, butyl rubber,polysulfide elastomer, acrylic elastomer, acrylonitrile elastomers,silicone rubber, polysiloxanes, polyester rubber, diisocyanate-linkedcondensation elastomer, EPDM (ethylene propylene diene rubbers),chlorosulphonated polyethylene, fluorinated hydrocarbons and the like.In one embodiment, recycled tire rubber is employed.

[0037] The epoxy/elastomer hybrid, when added to the sealant material,preferably is added to modify structural properties of the sealantmaterial such as strength, toughness, stiffness, flexural modulus, orthe like. Additionally, the epoxy/elastomer hybrid may be selected torender the sealant material more compatible with coatings such aswater-bome paint or primer system or other conventional coatings.

[0038] Rheology Modifier

[0039] Preferably, the sealant material includes one or more materialsfor controlling the rheological characteristics of the sealant materialover a range of temperatures (e.g., up to about 250° C.). When used, therheology modifier preferably is present in an amount up to about 40%,and more preferably between about 1 to about 20%, and still morepreferably less than about 10%. Of course, higher amounts are possibleas well.

[0040] In one embodiment, any suitable art-disclosed rheology modifiermay be used, and thus the rheology modifier may be organic or inorganic,liquid or solid, or otherwise. In a particularly preferred embodiment,the rheology modifier is a polymer, and more preferably one based uponan olefinic (e.g., an ethylene, a butylenes, a propylene or the like), astyrenic (e.g., a styrene-butadiene-containing rubber), an acrylic or anunsaturated carboxylic acid or its ester (such as acrylates,methacrylates or mixtures thereof; e.g., ethylene methyl acrylatepolymer). The rheology modifier may be provided in a generallyhomogeneous state or suitable compounded with other ingredients.

[0041] It may be possible to use certain acetates (e.g., EVA) inaccordance with the present invention for certain applications. However,it is preferably that the rheology modifier (or the entire sealant) besubstantially free of an acetate in view of the propensity fordecomposition at higher temperatures and the attendant potentialdeleterious release of acetic acid onto a painted surface.

[0042] Blowing Agent

[0043] One or more blowing agents may be added to the sealant materialfor producing inert gasses that form as desired an open and/or closedcellular structure within the sealant material. In this manner, it maybe possible to lower the density of articles fabricated from thematerial. In addition, the material expansion helps to improve sealingcapability.

[0044] The blowing agent may include one or more nitrogen containinggroups such as amides, amines and the like. Examples of suitable blowingagents include azodicarbonamide, dinitrosopentamethylenetetramine,azodicarbonamide, dinitrosopentamethylenetetramine,4,4_(i)oxy-bis-(benzenesulphonylhydrazide), trihydrazinotriazine andN,N_(i)-dimethyl-N,N_(i) dinitrosoterephthalamide. In a highly preferredembodiment, modified and unmodified azocarbonamides may be supplied tothe material 10 in particle form having particles sizes of, for example,120 and 180 microns. Advantageously, the azocarbonamides can assist thesealant material in leveling itself (i.e., forming a surface ofmaintaining the surface 24 in a substantially flat condition).

[0045] An accelerator for the blowing agents may also be provided in thesealant material. Various accelerators may be used to increase the rateat which the blowing agents form inert gasses. One preferred blowingagent accelerator is a metal salt, or is an oxide, e.g. a metal oxide,such as zinc oxide.

[0046] Amounts of blowing agents and blowing agent accelerators can varywidely within the sealant material depending upon the type of cellularstructure desired, the desired amount of expansion of the sealantmaterial, the desired rate of expansion and the like. Exemplary rangesfor the amounts of blowing agents and blowing agent accelerators in thesealant material range from about 0% by weight to about 5% by weight andare preferably in the sealant material in fractions of weightpercentages.

[0047] Curing Agent

[0048] One or more curing agents and/or curing agent accelerators may beadded to the sealant material. Amounts of curing agents and curing agentaccelerators can, like the blowing agents, vary widely within thesealant material depending upon the type of cellular structure desired,the desired amount of expansion of the sealant material, the desiredrate of expansion, the desired structural properties of the sealantmaterial and the like. Exemplary ranges for the curing agents or curingagent accelerators present in the sealant material range from about 0%by weight to about 7% by weight.

[0049] Preferably, the curing agents assist the sealant material incuring by crosslinking of the polymers, epoxy resins (e.g., by reactingin stoichiometrically excess amounts of curing agent with the epoxidegroups on the resins) or both. It is also preferable for the curingagents to assist in thermosetting the sealant material. Useful classesof curing agents are materials selected from aliphatic or aromaticamines or their respective adducts, amidoamines, polyamides,cycloaliphatic amines (e.g., anhydrides, polycarboxylic polyesters,isocyanates, phenol-based resins (such as phenol or cresol novolakresins, copolymers such as those of phenol terpene, polyvinyl phenol, orbisphenol-A formaldehyde copolymers, bishydroxyphenyl alkanes or thelike), or mixtures thereof. Particular preferred curing agents includemodified and unmodified polyamines such as triethylenetetramine,diethylenetriamine tetraethylenepentamine, cyanoguanidine and the like.An accelerator for the curing agents (e.g., methylene diphenyl bis urea)may also be provided for preparing the sealant material.

[0050] Filler

[0051] The sealant material may also include one or more fillers,including but not limited to particulated materials (e.g., powder),beads, microspheres, or the like. Preferably the filled includes arelatively low-density material that is generally nonreactive with theother components present in the sealant material.

[0052] Examples of fillers include silica, diatomaceous earth, glass,clay, talc, pigments, colorants, glass beads or bubbles, glass, carbonceramic fibers, antioxidants, and the like. Such fillers, particularlyclays, can assist the sealant material in leveling itself during flow ofthe material. The clays that may be used as fillers may include claysfrom the kaolinite, illite, chloritem, smecitite or sepiolite groups.Examples of suitable fillers include, without limitation, talc,vermiculite, pyrophyllite, sauconite, saponite, nontronite,montmorillonite or mixtures thereof. The clays may also include minoramounts of other ingredients such as carbonates, feldspars, micas andquartz. The fillers may also include ammonium chlorides such as dimethylammonium chloride and dimethyl benzyl ammonium chloride. Titaniumdioxide might also be employed.

[0053] In one preferred embodiment, one or more mineral or stone typefillers such as calcium carbonate, sodium carbonate or the like may beused as fillers. In another preferred embodiment, silicate minerals suchas mica may be used as fillers. It has been found that, in addition toperforming the normal functions of a filler, silicate minerals and micain particular.

[0054] When employed, the fillers in the sealant material can range from10% to 90% by weight of the sealant material. According to someembodiments, the sealant material may include from about 0% to about 3%by weight, and more preferably slightly less that 1% by weight days orsimilar fillers. Powdered (e.g. about 0.01 to about 50, and morepreferably about 1 to 25 micron mean particle diameter) mineral typefiller can comprise between about 5% and 70% by weight, more preferablyabout 40% to about 60%, and still more preferably approximately 55% byweight of the sealant material. In one highly preferred embodiment thesealant material may contain approximately 7% by weight mica.

[0055] Other Additives

[0056] Other additives, agents or performance modifiers may also beincluded in the sealant material as desired, including but not limitedto a UV resistant agent, a flame retardant, an impact modifier, a heatstabilizer, a colorant, a processing aid, a lubricant, a reinforcement(e.g., chopped or continuous glass, ceramic, aramid, or carbon fiber orthe like).

[0057] Other polymers may also be incorporated into the sealantmaterial, e.g., by copolymerization, by blending, or otherwise. Forexample, without limitation, other polymers that might be appropriatelyincorporated into the sealant material include halogenated polymers,polycarbonates, polyketones, urethanes, polyesters, silanes, sulfones,allyls, olefins, styrenes, acrylates, methacrylates, epoxies, silicones,phenolics, rubbers, polyphenylene oxides, terphthalates, or mixturesthereof. Other potential polymeric materials may be or may includeinclude, without limitation, polyethylene, polypropylene, polystyrene,polyolefin, polyacrylate, poly(ethylene oxide), poly(ethyleneimine),polyester, polyurethane, polysiloxane, polyether, polyphosphazine,polyamide, polyimide, polyisobutylene, polyacrylonitrile, poly(vinylchloride), poly(methylmethacrylate), poly(vinyl acetate),poly(vinylidene chloride), polytetrafluoroethylene, polyisoprene,polyacrylamide, polyacrylic acid, polymethacrylate, and polyacetals.

[0058] When determining appropriate components for the sealant material,it may be important to form the material such that it will only activate(e.g., flow, foam or otherwise change states) at appropriate times ortemperatures. For instance, in most applications, it is undesirable forthe material to be reactive at room temperature or otherwise at theambient temperature in a production environment. More typically, thesealant material becomes activated to flow at higher processingtemperatures. As an example, temperatures such as those encountered inan automobile assembly plant may be appropriate, especially when thesealant material is processed along with the other components atelevated temperatures or at higher applied energy levels, e.g., duringpainting preparation steps. Temperatures encountered in many coatingoperations, for instance, range up to about 250° C. or higher.

[0059] The present materials exhibit the ability to flow and self levelto then serve as a generally smooth paintable surface within atemperature range up to about 100° C., more preferably up to about 175°C., still more preferably up to about 250° C., and even still morepreferably up to about 325° C.

[0060] Formation of the sealant material can be accomplished accordingto a variety of new or known techniques. Preferably, the sealantmaterial is formed as a material of substantially homogeneouscomposition. However, it is contemplated that various combiningtechniques may be used to increase or decrease the concentration ofcertain components in certain locations of the sealant material.

[0061] According to one embodiment, the sealant material is formed bysupplying the components of the material in solid form such as pellets,chunks and the like, in liquid form or a combination thereof. Thecomponents are typically combined in one or more containers such aslarge bins or other containers. Preferably, the containers can be usedto intermix the components by rotating or otherwise moving thecontainer. Thereafter, heat, pressure or a combination thereof may beapplied to soften or liquidize the components such that the componentscan be intermixed by stirring or otherwise into a single homogenouscomposition.

[0062] According to another embodiment, the sealant material may beformed by heating one or more of the components that is generally easierto soften or liquidize such as the polymer based materials to inducethose components into a mixable state. Thereafter, the remainingcomponents may then be intermixed with the softened components.

[0063] Depending upon the components used, it may be important to assurethat the temperature of the components remains below certain activationtemperatures that might cause the sealant material to activate (e.g.,form gasses, flow or otherwise activate), cure (e.g., harden, stiffen orotherwise change states) or both. Notably, when the sealant materialcontains a blowing agent, it is typically desirable to maintain thetemperature of the sealant material below a temperature that willactivate the blowing agent during formation of the sealant material orbefore the sealant material is applied to a surface.

[0064] In situations where it is desirable to maintain the sealantmaterial at lower temperatures it may be desirable to maintain thecomponents in a semi-solid or viscoelastic state using pressure or acombination of pressure and heat to intermix the components of thesealing material. Various machines have been designed to applying heat,pressure or both to materials. One preferred machine is an extruder.According to one embodiment of the present invention, various componentsmay be premixed into one, two or more pre-mixtures and introduced at oneor various locations in a single or twin-screw extruder. Thereafter, theheat and pressure provided by the extruder mixes the sealant material ina single generally homogeneous composition, and preferably does sowithout activating the material.

[0065] As an example, and referring to FIG. 5, a first mixture 60 ofcomponents may be provided to a throat portion 54 of the extruder 40.Each of the components is preferably provided in solid forms such aschunks, pellets or powders that can be thoroughly mixed together in atumbler or other mixing receptade. The first mixture 60 may comprise anyof the components discussed above. In a preferred embodiment, the firstmixture 60 may include a combination of one or more components, whichmay be chosen from an epoxy resin, an epoxy/elastomer, a filler, anotherpolymer or a mixture thereof.

[0066] As the first mixture 60 is introduced into the extruder 40, theextruder screw 70 mixes the components to form a viscoelastic materialthat is progressively moved from the throat portion 54 of the extruder40 and through the intermediate portion 58 of the extruder. Aftersubstantial mixing of the first mixture 60, a side stream that ispreferably liquid is provided to enhance mixing of the components in theextruder 40. The side stream preferably provides an epoxy in resin formthat may or may not be combined with other components. Alternatively,the side stream may include any of the polymer materials discussedabove.

[0067] Toward the die portion 48 of the extruder 40, a second mixture 90is combined with the first mixture 60 and the material from the sidestream. Again, each of the components is preferably provided in solidforms such as chunks, pellets or powders that can be thoroughly mixedtogether in a tumbler or other mixing receptacle. Moreover, the secondmixture 90 is a combination of one or more of the same components thatwere supplied in the first mixture 60. Additionally, however, anyblowing agents, blowing agent accelerators, curing agents or curingagent accelerators are preferably added to the second mixture 90.

[0068] Once the first mixture 60, the side stream and the second mixture90 are combined and mixed, they form the sealant material, which may beemitted from the extruder 40. The sealant material may then betransported and applied to substrates or, in certain circumstances, thematerial may be directly applied to a surface as it leaves the extruder40. The skilled artisan will recognize that various other techniques maybe used to form the sealant material from the various components.

[0069] FIGS. 1-4 illustrate an example of a sealant material 10 beingapplied to a substrate 12. The sealant material 10 may be applied to avariety of substrates. However, for exemplary purposes and with nointention of limiting the invention, the material 10 is shown as appliedto components 14, 16 (e.g. overlapping panels) for forming a joint 18.The joint 18, as shown, is formed with overlapping arced portions of thetwo components 14, 16. In one embodiment, the substrate material isselected from steel, aluminum or plastic (e.g., reinforced plastic).

[0070] The sealant material 10 may be initially formed in a variety ofshapes, sizes, patterns, thicknesses and the like and may be formedusing a variety of forming techniques such as molding, extruding,thermosetting and the like. Alternatively, the sealant material 10 maybe initially formed in a substantially liquid state wherein the material10 is shaped by its container or shaped by a substrate to which thematerial has been applied. Preferably, the sealant material 10 isinitially formed as a single homogeneous melt flowable composition,however, in alternative embodiments, the sealant material 10 may formone layer of a multi-layer article. The sealant material 10 may be dryto the touch shortly after it is initially formed to allow easerhandling, packaging and the like of the material 10, however, it is alsopossible for the material 10 to be wet, tacky or both. In one preferredembodiment, shown in FIG. 1, the sealant material 10 has been extrudedin a viscoelastic state as an elongated strip, which is shown incross-section. Of course other section shapes (e.g., having anasymmetrical shape about a longitudinal axis, a symmetrical shape aboutthe longitudinal axis, varying shapes along the longitudinal axis,longitudinal channels or passages, or the like) are contemplated as welland may be formed as desired or needed for any chosen application. Itmay also be possible to co-extrude the sealant material with a strip orwire (e.g., for forming an encapsulated or laminated strip or wire, suchas for making an antenna for a communications system). Molded or die-cutarticles may also be formed from the sealant material of the presentinvention.

[0071] Once the sealant material 10 has been formed in a desiredconfiguration, the material may be activated, cured or both to form aseal of a desired configuration. Activation of the sealant material,curing of the material or both may take place in a single stage ormultiple stages and may utilize a variety of stimuli to cause activationor curing. Activation, as used herein, generally denotes inducing thesealant material 10 to flow, foam or generally soften and can be causedby exposure of the sealant material 10 to a variety of stimuli such asheat, light, electricity, pressure, moisture and the like. Curing, asused herein, generally denotes any stiffening, hardening, solidifying orthe like of the sealant material and can be caused by exposure to avariety of stimuli such as cooling, light and the like.

[0072] Activation of the material may include at least some degree offoaming or bubbling in situations where the sealant material includes ablowing agent. Such foaming or bubbling can assist the sealant materialin wetting a substrate and forming an intimate bond with the substrate.Alternatively, however, it shall be recognized that the sealant materialmay be activated to flow without foaming or bubbling and may stillsubstantially wet the substrate to form a desired seal.

[0073] According to one embodiment, the sealant material may beactivated prior to application of the sealant material to a substratesuch that the sealant material is in a generally flowable state when itis applied to the substrate. In such a situation, curing of the materialmay occur during or after the time the sealant material is applied tothe substrate.

[0074] According to another embodiment, the sealant material 10 mayundergo a single stage activation, a single stage cure or both. In theembodiment, the sealant material is typically placed adjacent (e.g., indirect contact with or near) a substrate upon which the sealant materialis to form a seal. Thereafter, the sealant material 10 is activated byexposure to a stimulus such as energy in the form of heat, light orotherwise that activates the sealant material 10 to flow over thesubstrate. Then, after a desired amount of flow has been induced, thesealant is cured substantially throughout its volume to form a seal uponthe substrate.

[0075] According to still other embodiments, the sealant material 10 mayundergo a selective multiple stage activation, a multiple stage cure orboth. For example, a portion of the sealant material 10 may be exposedto a stimulus to at least partially cure a portion of the sealantmaterial, e.g. a cure to a predetermined depth (e.g., on the order ofabout 1 mil to about 2 mm), or a cure in certain regions along or withinthe mass of material. In FIG. 2, the sealant material 10 is illustratedwith a partially cured portion 20 that was formed by exposing at leastone portion of the surface 24 of the sealant material to ultraviolet(UV) light, UV radiation, moisture, infrared light, heat or the likefrom a stimulus source to cross-link or otherwise cure the partiallycured portion 20. As can be seen, the remainder of the sealant material10 forms a second portion 26, which can be cured at a later time ordifferent location.

[0076] Alternatively, the partially cured portion 20 may be formed byexposing a surface of the sealant material 10 to a stimulus (e.g., heat)that first activates (e.g.,softens) the portion 20 and then the portion20 may be exposed to another stimulus (e.g., cooling) for curing.Preferably, the amount of heat used to activate the portion 20 is enoughto soften the portion 20 without causing any substantial degree of flow.In this manner, the sealant material 20 can generally maintain the shapein which it was originally formed until it is later activated to flowover a substrate.

[0077] The partially cured portion 20 may be formed to most any depthwithin the sealant material 10 depending on the stimulus applied to theportion 20, the length of time of exposure to the stimulus and the like.Moreover, the length or depth of the selectively or partially curedportion 20 may be varied at different locations of the sealant material10 as desired or depending upon the substrate to which the material 10is being applied.

[0078] One particularly advantageous feature of the present invention isthe ability to cure the present materials in the absence of aphoto-initiator. Thus, while photoinitiators might be employed in someapplications, in one preferred embodiment, the composition of thepresent invention is substantially free of a photoinitiator.

[0079] Curing or partial curing of the sealant material may also beeffected using an acid cure for inducing homopolymerization on or withinthe material, or with a suitable liquid for effectuating the initiationof a condensation reaction. By way of example, a partial cure of asurface of the sealant material may be undertaken with any suitableacid, but more preferably with a mild acid (such as phosphoric acid,citric acid or the like). It may also be performed by coating with awater dispersed or 100% amine-based liquid curing agent suitable forcondensation polymerization. Under either approach, the liquid mayoptionally be rinsed after application.

[0080] Before or after formation of the partially cured portion 20, thesealant material 10 is is typically placed adjacent the substrate 12such that the melt flowable portion 26 of the substrate 12 will bepermitted to flow over a portion of the substrate 12. In FIG. 3, thestrip of sealant material 10 is placed in the channel 18 such that alength of the strip extends along a length of the channel 18 and suchthat a width of the strip generally spans a width of the channel 18.Preferably, the melt flowable portion 26 is directly adjacent theoverlapping portion of the panels 14, 16 and the partially cured portion20 of the sealant material 10 faces out of the channel 18.

[0081] Once the sealant material 10 is situated as desired, the material10 is exposed to heat or elevated temperature, such as from an e-coatprocess or otherpaint operation cycle thereby causing the flowableportion 26 to cover a portion of the substrate 12. In FIG. 4, thesealant material 10 is shown after it has been heated to a flowablestate permitting the material 10 to intimately contact the overlappingportions of the panels 14, 16.

[0082] The sealant material of the present invention may be employed inany suitable thickness (e.g., from about 1 mil to about 10 mm, and morepreferably about 1 to 5 mm).

[0083] In one particularly preferred embodiment, a sealed joint preparedin accordance with the present invention is further coated with a topcoat (e.g., a paint) and optionally a primer (between the top coat andthe joint), a clear coat (e.g., a polyurethane, an acrylic such as aglycidyl methacrylate (GMA)-based coating, or a mixture thereof) overthe top coat, or a combination thereof. Preferably one such coating is awater-based coated, although solvent based coatings may also be used. Inone embodiment, the coating includes a two component polyurethanecoating. In another embodiment the coating is applied as a powdercoating. Preferably an electocoating process is used to apply a coatinglayer, such as the primer.

[0084] The preferred embodiment of the present invention has beendisclosed. A person of ordinary skill in the art would realize however,that certain modifications would come within the teachings of thisinvention. Therefore, the following claims should be studied todetermine the true scope and content of the invention.

What is claimed is:
 1. An article of manufacture; comprising: a) a firstpanel; b) a second panel adjoining said first panel; c) a sealant oversaid first panel and said second panel; said sealant material includingi. up to about 80% of an epoxy resin; ii. up to about 40% of anepoxy/elastomer hybrid; iii. up to about 40% of a rheology modifier; iv.up to about 5% of a blowing agent; v. up to about 7% of a curing agent;and vi. a filler; d) a layer of primer over said sealant; and e) a layerof paint over said primer.
 2. An article of manufacture, comprising: a)a first panel; b) a partially cured sealant over said first panel andsaid second panel; said sealant material including i. up to about 80% ofan epoxy resin; ii. up to about 40% of an epoxy/elastomer hybrid; iii.up to about 40% of a rheology modifier other than an ethylene vinylacetate; iv. up to about 5% of a blowing agent; v. up to about 7% of acuring agent; and vi. about 40 to about 60% of a filler, said sealantbeing substantially free of a photoinitiator.
 3. An article ofmanufacture, comprising: a) a first metal automotive vehicle panelselected from aluminum, steel or reinforced plastic; b) a secondautomotive vehicle panel selected from aluminum, steel or reinforcedplastic adjoining said first panel; c) a sealant over said first paneland said second panel; said sealant material including
 1. about 10 toabout 50 parts by weight of an epoxy resin;
 2. about 10 to about 30parts by weight of an epoxy/elastomer hybrid having about 1:3 to 3:1parts of epoxy to elastomer;
 3. less than about 10 parts by weight of arheology modifier including an acrylic;
 4. up to about 5 parts by weightof an azocarbonamide blowing agent;
 5. up to about 7 parts by weight ofa curing agent including an amine; and
 6. about 40 to about 60 parts byweight of a mineral filler; d) a layer of primer, applied byelectrocoating, over said sealant; e) a layer of two componentpolyurethane paint over said primer; and f) a clear coat layer over saidpaint.
 4. The article of claim 1, wherein said sealant is substantiallyfree of a photoinitiator.
 5. The article of claim 1, wherein saidsealant is substantially free of ethylene vinyl acetate.
 6. The articleof claim 1, wherein said sealant is substantially free of ethylene vinylacetate and a photoinitiator.
 7. The article of claim 1, wherein saidsealant has been partially cured.
 8. The article claim 2, wherein saidepoxy resin is present in an amount of about 10 to about 50% by weight,and said epoxy/elastomer hybrid is present in an amount of about 10 toabout 30% by weight and has about 1:3 to 3:1 parts of epoxy toelastomer.
 9. The article of claim 8, wherein said filler is a mineralfiller.
 10. The article of claim 3, wherein said sealant issubstantially free of a photoinitiator.
 11. The article of claim 3,wherein said sealant is substantially free of ethylene vinyl acetate.12. The article of claim 3, wherein said sealant is substantially freeof ethylene is vinyl acetate and a photoinitiator.
 13. The article ofclaim 3, wherein said sealant has been partially cured.
 14. The articleof claim 3, wherein said sealant is self leveling at elevatedtemperatures for providing a smooth paintable surface.